While there are existing patents that try to solve the spreading of germs on a door knob/handle, none are practical or commercially viable. Many known previous devices are stand-alone units that replace an existing door knob/handle. This presents at least two problems: first, it is not a quick and easy install, eliminating a portion of the population that is willing to install the device themselves; secondly, it limits the market considerably, as individuals are forced to accept the aesthetics of a device that contain the packaged door knob/handle instead of using their existing door knob/handle in a retrofit application. For instance, some previous patents are stand-alone devices only in the shape of a doorknob. This limits the market as those who have door handles will likely not use that product.
Previous patents only addressed one side of the door knob/handle. While an additional device can be placed on the opposite side of the door, there is no direct communication or sequencing that allows this device to effectively eliminate microorganisms on both sides of the door, given the possibility that only one side of the door is sanitized defeating the purpose of the product; stopping the spreading of germs through contact with door knobs/handles. To provide a pragmatic and effective solution, both sides of the door would need to be sanitized.
Many previous patents disclose devices which are mechanical in nature which presents maintenance issues, increases the weight, and adds to bulkiness of the device while consuming significantly more energy.
Using an infrared sensing device as indicated in a previous patent is an imperfect solution, as the dominant hand of the person opening the door could be on the opposite side of the sensing device and hence not sensed. Infrared sensing devices have other issues that can lead to devices disclosed in previous patents not functioning as intended all the time.